Bernie Sanders questioned President Barack Obama’s leadership in a new interview, suggesting that he would be able to close a divide between Americans and government that the Obama administration has left open throughout his presidency.

It’s the latest salvo from Sanders, who has — intentionally or unintentionally — been engaging in an escalating war of words with the man who eight years ago was building his own political revolution.

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“There’s a huge gap right now between Congress and the American people,” Sanders said Wednesday in an interview with MSNBC that will air Thursday evening on “The Last Word with Lawrence O’Donnell.” “What presidential leadership is about [is] closing that gap.”

Sanders acknowledged that Obama has tried to bridge the divide but said he hasn’t succeeded. “But I think what we need, when I talk about a political revolution, is bringing millions and millions of people into the political process in a way that does not exist right now,” he said.

Such a political revolution would be necessary to carry out his agenda, Sanders said, which includes free college and a single-payer health care system.

Hillary Clinton, who has recently been more openly embracing Obama and his legacy, pounced on Sanders’ comments. She fired off a tweet that served as a double whammy by invoking Marco Rubio’s robotically repeated line from last Saturday’s GOP debate. “Let's dispel with this fiction that @POTUS doesn't know what he's doing. He knows exactly what he's doing,” she said, including a link to the MSNBC interview.

Obama has increasingly found himself caught in the crossfire between Sanders and Clinton, and at times has injected himself, usually to the detriment of Sanders.

During an interview with POLITICO last month, Obama quickly shot down the notion that Sanders, with his grass-roots revolution, reminded him of himself in 2008. “I don’t think that's true,” he said. And he made clear during that conversation that he views Clinton, not Sanders, as the candidate best suited to take the baton from him.

Sanders, in the interview with MSNBC, said Obama and Vice President Joe Biden should stay out of the Democratic primary and let the process play out. “Well, I hope and expect that the president will allow the American people to make the decision as to who the Democratic nominee will be,” he said. “What the president has indicated, what Vice President Biden has indicated publicly, is that they are going to play a neutral role in the process, which is what they should be playing.”

The Vermont senator and Obama have generally maintained a cool but not unfriendly relationship. Sanders had a one-on-one meeting with Obama in the Oval Office just five days before the Iowa caucuses, and both sides said it was a good encounter.

Tad Devine, a top aide to Sanders, told POLITICO on Thursday that the Vermont senator has been “very supportive” of the president. He said Sanders is also sympathetic about the challenges he faced when he entered the White House, including a dismal economy and two wars he inherited.

“He thinks the president has done a great job given the circumstances that he and the vice president came into. And we're not trying to signal anything other than how Bernie would lead the nation if he was president,” Devine said.

Despite those words of reassurance, there’s other evidence of tension rising between the two men.

Obama allies lashed out at Sanders after the release of liberal radio host Bill Press' book "Buyer's Remorse: How Obama Let Progressives Down,” which featured Sanders’ above-the-title blurb — "Bill Press makes the case ... Read this book.” Sanders’ full quote was more nuanced, but some damage was done.

And while the White House denied it was a shot at Sanders, Obama on Wednesday called out people who accuse rivals not being “a real progressive” during his speech calling for civility in politics. (Sanders has accused Clinton of being a progressive only on “some days.”)

Sanders maintains he has declined numerous occasions to take personal shots at Clinton but signaled her intensifying attacks as evidence that her campaign is worried. “Well, I think it really talks a little bit about the disarray within the Clinton camp. If you’re confident of your views on the issues, then you don’t have to get into very negative-type campaigns,” he said during the interview. “But we have seen in the last few days the very significant increase in the level of negativity coming from the Clinton campaign, and that tells me that they perceive themselves to be in trouble.”

“The idea of Bernie Sanders, who has little to show for his 25 years in Congress, giving leadership lectures to President Obama is absurd,” press secretary Brian Fallon tweeted.

The back-and-forth over Obama’s legacy is likely to be a prime topic of Thursday night’s Democratic debate in Milwaukee, where Clinton and Sanders will square off for the first time since the New Hampshire primary.